Abstract: A tribo-electro-gas-dynamic powder coating apparatus with an obstruction-free barrel having a semi-toroidal section throat at the inner end and having an opening at the outer end. An end cap is connected to the barrel end over the semi-toroidal section to form an annular chamber circumferentially surrounding the semi-toroidal section and having a clearance between the section and the end cap leading from the chamber to the barrel bore.

Abstract: A method and apparatus for the leak testing of one or more filters, and comprising a housing adapted to sealably mount the filters, means for introducing DOP particles within the housing and immediately upstream of each of the filters, and means for imparting a like electrical charge to the particles such that the particles repel each other and rapidly disperse within the airstream so as to be substantially uniformly dispersed upon reaching the face of each filter. A collecting surface may be disposed downstream of the filters for detecting any of the charged particles to thereby permit a determination as to whether the filters are leaking. Alternatively, a collapsible panel system may be positioned immediately downstream of the filter to condense and impart turbulence to the airstream to thereby permit a sample to be withdrawn for analysis from a point closely adjacent the filter.

Abstract: The disclosure relates to an improved electrostatic paint spray system adapted for the application of conductive materials while at the same time providing for isolation of the electrically charged spray heads from the source of coating material. Heretofore, electrostatic paint spray procedures have been limited to a large extent to the use of non-conductive coating materials. Where it is appropriate or desirable to utilize conductive coating materials, it has been necessary to provide for the electrical isolation of the entire paint supply system, a circumstance which imposes severe practical limitations. The present invention enables an isolating stage to be provided within the coating material supply system, near the area of discharge, so that the "upstream" portions of the supply system are free of the high voltage electrical charge impressed at the spray guns, notwithstanding the use of electrically conductive coating materials.

Abstract: An electrostatic spray coating system for spraying conductive coatings such as water base paint has a grounded paint supply sub-system which intermittently supplies conductive coating material to a high voltage sub-system across an air space. An interlock system prevents conductive coating material from being transferred from the grounded sub-system to the high voltage sub-system while high voltage electrical potentials being applied to the high voltage coating material sub-system.

Abstract: A system for electrostatic spraying of liquids, such as agricultural pesticides, paints and other liquids, which relies on a novel spray nozzle that combines pneumatic atomization and electrostatic induction charging to provide a stream of electrostatically charged fine droplets. The nozzle uses a low voltage power supply, e.g. a 12 volt battery, electronically raises the voltage to a level in the range of several hundred to several thousand volts, and applies the high voltage to an annular induction electrode which is embedded in the spray nozzle. The high voltage components are inside the nozzle, which is made of an electrically insulating material, to minimize the danger of shock and the possibility of mechanical damage to the high voltage components. The spray nozzle operates at a relatively low voltage and at a low input power, but provides a droplet stream at a high droplet charging level, for effective and uniform deposition of the sprayed liquid onto the target.

Abstract: Electrostatic deposition of air atomized liquid coating materials by adjusting the conductivity of the coating material and the voltage applied thereto so that virtually no air ionization occurs. Thus, essentially all of the current reaching the object to be coated is carried by the sprayed material thus minimizing the charge build-up on the subject, and eliminating charge accumulation on ungrounded objects out of the spray zone.

Abstract: The disclosure relates to automatic paint spray systems, typically but not necessarily of the electrostatic type, provided with color change means and facilities for recovery and re-use of the residual paint increment contained in the system at the start of a color change cycle. The system of the invention provides for an automatic color change cycle in a paint spray system, in which original paint is purged from the system by terminating the supply of the original paint and introducing purge fluids, including solvent and possibly also air. Principally, the original paint is purged through a discharge line, on the downstream side of the paint spray devices, and is collected in a suitable receptacle, along with the purged solvent. A unique feature of the new system resides in the ability of the discharge system to automatically separate and isolate the original paint from the new color paint, so that the purged paint may be collected in a segregated container and re-used.

Abstract: Apparatus is provided for applying a well-defined strip of thermoplastic adhesive in powder form to a substrate. Powdered adhesive material is received from a hopper supply into compartments arranged around the periphery of a rotatable transporter wheel. The wheel, by rotation, carries the adhesive to a delivery station where, owing to the presence of a strong electrostatic field between the wheel and an electrode, the adhesive is drawn from the wheel compartments and onto the substrate, to which it adheres. The substrate is moved through the apparatus at an appropriate speed, in comparison with that of rotation of the wheel, such that a continuous uniform strip of adhesive is applied to the substrate.

Abstract: A coating apparatus with a powder supply system for use in a device for electrostatically spraying powder material onto the surface of an article or substrate to be coated. The system includes a powder reclaiming and recycling system which pneumatically retrieves the unused powder from the spray booths and filters the powder from the air. The filter system includes plural modules, each capable of accommodating a given number of spray guns. An automatic filter shaking system releases the powder from the filters upon command by sequentially shutting down the filter modules, one at a time, while the system is in operation. An additional filter module is provided so that adequate filtering capability is maintained while the filter shaking operation proceeds. The powder released from the filters is blown from the filters to a feeder section through a sieve which mixes new powder with the reclaimed powder under automatic control which replenishes the powder supply to the feeder.

Abstract: In an installation for the electrostatic projection of powders for coating objects, a method of improving the efficiency of projection and deposit of the said powders consists of increasing the relative humidity of the projection gas in the immediate vicinity of the projection nozzle by means of mixing the jet of gas which conveys the coating powder, at the level of the projection nozzle, with a jet of auxiliary gas previously heated and humidified by means of an appropriate liquid. In an alternative method, there is comprised the further step of reducing the temperature of the main jet of gas before this main jet is mixed with the auxiliary gas.The apparatus for carrying the method into effect comprises the heating and humidifying devices for the auxiliary gas and a device for cooling the main gas.

Abstract: An electrostatic spray gun for liquid paint has a nozzle that comprises an inner body formed of a sintered material that consists of an electrically non-conductive matrix, e.g. polytetrafluoroethylene, with conductive particles, e.g. bronze powder, dispersed in the matrix, and an outer body of electrically insulating plastic material. The rear end of the inner body is connected to high voltage, and it has an annular front surface around a paint discharge orifice. This surface shows a lot of such bronze particles that form point electrodes for producing air ions. Two additional needle electrodes are clamped between the two bodies. The paint is dispersed by air jets and the air ions attach to the paint particles.

Abstract: Apparatus for spraying a predetermined amount of paint, especially electroconductive paint as used for coating metal anodes, which comprises in combination an electrostatic spray gun and a paint delivery device for the gun which operates on a single displacement diaphragm principle.

Abstract: The disclosure relates to an improved electrostatic paint spray system adapted for the application of conductive materials while at the same time providing for isolation of the electrically charged spray heads from the source of coating material. Heretofore, electrostatic paint spray procedures have been limited to a large extent to the use of non-conductive coating materials. Where it is appropriate or desirable to utilize conductive coating materials, it has been necessary to provide for the electrical isolation of the entire paint supply system, a circumstance which imposes severe practical limitations. The present invention enables an isolating stage to be provided within the coating material supply system, near the area of discharge, so that the "upstream" portions of the supply system are free of the high voltage electrical charge impressed at the spray guns, notwithstanding the use of electrically conductive coating materials.

Abstract: An electrostatic spray apparatus and method for spraying electrically conductive coating materials on a continuous basis from an electrically grounded bulk coating supply.